Fig. 1

Symptom and morphology of the spruce dwarf mistletoe. a Typical symptoms of spruce dwarf mistletoe. Branches at the bottom firstly display witches’ brooms on a mature Qinghai spruce (double dot lines). b Dieback of branches and death of the entire tree. c Spruce dwarf mistletoe parasites on a live stem of a spruce. d The swelling of a infected stem. E-I represents shoots (e) pistillate flowers (f) staminate flowers (g) Fruits (h) seeds (i) of the spruce dwarf mistletoe for collecting samples. j A seed attached onto the stem